Soft screw anchor



Nov. 8, 1966 J. B. WAGNER SOFT SCREW ANCHOR 2 Sheets-s 1 Filed June 4, 1964 INVENTO JOHN WAGNE Nov. 8, 1966 J. B. WAGNER SOFT SCREW ANCHOR 2 Sheets-Sheet 2 Filed June 4, 1964 INVENTOR.

JOHN B.WAGNER United States Patent 3,283,641 SOFT SCREW ANCHOR John B. Wagner, 40 Parkland Drive, Walnut Creek, Calif. Filed June 4, 1964, Ser. No. 372,471 4 Claims. (CI. 8570) The invention relates to screw anchors of the kind to be inserted in prepared openings in walls, floors, ceilings, and other surfaces.

An object of the present invention is to provide an anchor of the character described which can be made from inexpensive materials, manufactured by extrusion processes, easily installed and will provide a secure mounting for a fastener :by mechanically gripping the back wall face as well as frictionally grip the side walls of a passage through the wall.

Another object is to provide an anchor which can be adapted to fit large holes by expanding one anchor or inserting additional anchors side by side or can be inserted into smaller holes by collapsing the anchor.

Still another object of the present invention is to provide an anchor which is made of soft material which can be easily cut with a pocket knife so that it can be adapted to fit walls of varying thicknesses yet is highly durable being resistant to acids, fungus, water and climatic conditions.

Yet another object of the present invention is to provide an anchor having a uniform cross section which will deform and grip the side walls of a passage in a wall.

The invention possesses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of this specification. It is to be understood however, that variations in the showing made by the said drawing and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings (two sheets):

FIGURE 1 is a side elevation of an anchor constructed in accordance with the present invention.

FIGURE 2 is an end view of the anchor shown in FIGURE 1.

FIGURE 3 is a side elevation of an anchor in place in a stressed condition showing the wall in cross section.

FIGURE 4 is a side elevation of an anchor showing a screw partially inserted therein.

FIGURE 5 is a side elevation of an anchor in place in a stressed condition showing a wall of another type in cross section.

FIGURE 6 is a side elevation of a modified form of the present invention.

FIGURE 7 is an end elevation of the anchor shown in FIGURE 6.

FIGURE 8 is a side view of an anchor of the present invention with parts broken away and showing the anchor immediately after seating of a screw in a fragmentary cross section of a wall.

FIGURE 9 is a side elevation of an anchor in place with parts broken away and showing the anchor in a stressed condition in a fragmentary cross section of a wall.

The screw anchoring device of the present invention for anchoring in a passage in a wall consists briefly of an elongated tubular member 6 of soft elastic material formed with a bore 7 "and a plurality of radially projecting slots 8 extending from bore 7 and having a lead portion 9 dimensioned to extend beyond a rear face 11 of a wall 12, member 6 being adapted for axial receipt of a self-tapping headed screw 13 thread-ably engaging the walls of bore 7 whereby member 6 is expanded into 3,283,641 Patented Nov. 8, 1966 ice frictional engagement with a wall of passage 16 to prevent rotation of member 6, the material and form of member 6 functioning to foreshorten and twist in lead portion 9 upon rotation of screw 13 when face 17 of head 8 is in engagement with an end 19' or bracket 41 for deforming lead portion 9 into locking engagement with rear face 11 of wall 12.

An important feature of the present device is the fact that it can be made inexpensively by extrusion processes. The anchor is therefore designed so that the outside diameter of member 6 and inside diameter of bore 7 are of constant diameter, the slots 8 are of constant depth and width and the web sections 22 are of constant thickness. Since the device has a constant cross section, members of varying length can be made merely by cutting the tubular member at a predetermined length. The material is soft enough that it can be cut with a pocket knife.

Various anchor shapes may be used with varying dirnensions and the member shown in FIGURE 2 is illustrative of one of these shapes. A table setting forth dimensions for this particular shape is set forth below for several common size, anchors. Referring to FIG- URE 2, A represents the web thickness 22, B represents the thickness .at the widest portion between the slots 8, C represents the distance between the bore 7 and the outer circumference 21, and D represents the width of the slot 22. All dimensions are given in inches.

Anchor Size A i B l C I D Min 005 130 040 045 020 140 055 060 010 .175 060 .055 Max O25 195 075 080 M1 010 .210 075 070 Max 030 235 090 (.375):

Min 015 .260 .090 085 Max 035 290 The screw 13 used with member 6 may be any screw such as a self-tapping slotted head sheet metal screw. The screw should be selected to threadably engage the walls of bore 7 and to exp-and the member into frictional engagement with the walls of passage .16. For a inch anchor, a No. 6, No. 8 or No. 10 screw may be used. For a inch anchor, at No. 10, No. 12 or No. 14 screw may be used.

The material used in member 6 must be such as to permit expansion of the outer surface 21 so that the member will frictionally engage a passage in the wall, it must have a low coefficient of friction with a metal screw and be easily tapped by the screw so that the member 6 will not turn in the passage as the screw is being thre-adably inserted in the member, and finally and most importantly, the material must be soft and elastic so that upon rotation of the fully inserted screw the lead portion 9 will foreshorten and deform into locking engagement with the back face 11 of the wall. It has been found that a medium molecular weight polyvinyl chloride resin containing dioctyl phthalate, epoxy-ester plasticizer of low temperature flex, barium caxlmium stabilizer, stearic acid and color pigment as required gives the desired characteristic properties. The physical properties of this material are typical of a high quality semirigid vinyl. The hardness is about 43-52 Shore D and the tensile strength of the product will be around 2700- 2800 p.s.i. Elongation at break will be about 230 to 250%. This material is inert to most acids, alka'lies, water, and ozone and a wide variety of aliphatic solvents.

The length of the screw and member 6 should be "chosen to'extend about'Vz inch beyond the back face 11 of the wall. For the and A inch size anchors and inch for the 5A and size anchors this gives s-uflicient length to impart a twist and deformation in the lead portion 9 of member 6.

Slots 8 formed in member 6, perform three important functions. First, the provision of slots cuts dO'WH on the surface contact area with screw 13 thus reducing the twisting force as the self-tapping screw is threadably inserted. Secondly, the provision of slots makes it possible to collapse the member 6 so that it may be inserted more easily into holes which may have a diameter slightily less than the unstressed diameter of the member 6. Thirdly, the provision of slots form web portions 22 which provide weakened planes in the member so that upon rotation of screw 13 when end 19 is in engagement with surface 17 of head 18 the unconfined leading portion 9 will twist.

The method of effecting an anchorage in a wall having a passage theret-hrough comprises briefly the steps of inserting in a passage a tubular member 6 having a length providing an end 19 adjacent a front face 26 of wall 12 and a lead portion 9 extending from a rear face 11 of the wall and being composed of a soft elastic material, threadably inserting a selfatapped headed screw 13 having a length greater than the passage axially through member 6 and expanding an outer surface 21 of the member into frictional engagement with the walls of passage 16 to prevent rotating of member 6, seating head 18 against end 19 of member 6 or against a bracket or washer 41 and rotating the seated screw 13 causing a lead portion 9 to twist creating a distortion in the portion in engagement with :back wall face 11 for preventing withdrawal of member 6. Further rotation of the seated screw causes a fioreshortening in portion 9 creating an enlargement in engagement with back wall face 11.

The anchoring device of the present invention may be used in either soft or hard'wall materials and even may be used in hollow core materials so long as there is sufficient thickness of the wall passage to prevent rotation of the member as the screw is threadably inserted. FIG- URE 3 shows the use of the anchor in a relatively soft material such as gypsum board. It will be noted that .some twisting of member 6 occurs in the wall 12.

' FIGURE 5 shows .the use of the screw anchor in a relatively'hard wall such as concrete, brick, tile, mortar, stone, fibreglass, wood or metal in which an insubstantial amount of twisting occurs in wall 12.

Phenomenal holding power has resulted from the use of the screw anchor and tests have shown that a 1 inch anchor will hold over 120 pounds and a A inch anchor willhold over 140 pounds in a /2 inch gypsum board. Certified laboratory tests have also shown that a screw anchor of the present design will hold 1600 pounds in concrete. An ordinary screw threadably inserted into a /2 inch'sheet rock wall has very little holding power. Yet,

when a 3/ inch anchor is inserted in the wall and a screw inserted thereinwith a handle attached to the screw, it is extremely difiicult to physically pull the screw out of the wall without using mechanical leverage;

Where the diameter of the passage in the wall is greater than the'unstressed diameter of member 6, screw 13 may be started in bore 7 so as to expand the outside diameter prior to inserting the member 6 in the wall passage. This method is shown in FIGURE 4.

: It has also been found that biasing an end of a member forming a sharpened surface 31, as shown in modified form 6a in FIGURES 6, 8 and 9, aids in the insertion of the member into the passage; In most instances, the member may be inserted by hand, but the material is such that the member may even be inserted by hammering on end 19. i

It has been found that the anchor constructed in accordance with the present invention provides a holding force greater than prior art devices which merely expand radially into frictional engagement with the walls of a passage in a material such as gypsum board even where the anchor 6 or 6a does not extend completely through the wall 46. As seen in FIGURE 8, the anchor of the present invention tends to elongate as screw 13 is inserted into the passage. This elongation is denoted d and will be greater in a rigid material. such as concrete than in a semirigid material such as gypsum board. The frictional engagement of anchor 6a in engagement with bore wall 16 prevents anchor Go from rotating. When the surface 17 of head 18 of screw 13 or surface 42 of bracket 41 seats against end 19 there is further frictional force to prevent end 19 from rotating.

As seated screw 13 is rotated, the lead portion 9 foreshortens in the direction of the screw head 18. Because the entire anchor is confined, as shown in FIGURE 9, there is less pronounced twisting than shown in FIGURES 3 and 5, but there is sufiicient twisting and deformation in the lead portion to give unusual holding power. The amount of twist and increase in diameter which causes the anchor to interlock with the bore wall will vary with the hardness of the wall material.

I claim: 1. A screw anchoring device for anchoring in a passage in a wall comprising:

an elongated tubular member of soft elastic material with a substantially smooth uninterrupted cylindrical exterior surface and having a hardness ranging between 43-52 Shore D formed with a bore and a plurality of internal radially projecting slots extending from said bore and having a lead portion dimensioned to extend beyond a rear face of said wall,

said member being adapted for axial receipt of a headed screw threadably engaging the walls of said bore whereby said member is expanded into frictional engagement with a wall of said passage to prevent rotation of said member,

and said material and form of said member functionin to foreshorten and twist in said lead portion upon-rm tation of said screw when said head is in engagement with an end distant from said lead portion for deforming said lead portion into locking engagement with said rear face of said wall. 2. A screw anchoring device for anchoring in a passage in a wall comprising:

an elongated tubular member of soft elastic material with a substantially smooth uninterrupted cylindrical exterior surface and having a hardness ranging between 43-52 Shore D formed with a bore and a plurality of internal radially projecting slots extending from said bore and having a lead portion extending beyond a rear face of said wall,

an elongated headed screw having a length greater than the length of said passage formed for threadably engaging the walls of said bore and dimensioned to expand said member into frictional engagement with a wall of said passage for preventing rotating of said member and having a fully inserted position wherein said head is in engagement with an end of said member,

said material and form of said member functioning to foreshorten and twist in said lead portion upon rotation of. said screw in said fully inserted position for deforming said lead portion into locking engagement with said rear face of said wall. v

3. A screw anchoring device for anchoring in a passage in a wall comprising:

an elongated tubular member of poly vinyl chloride with a substantially smooth uninterrupted cylindrical exterior'surface and having a hardness ranging between 43-52 Shore D formed with a bore and plurality of internal radially projecting slots extending from said bore terminating just short of an outer wall of said member so as to define flexible web sections and having a lead portion extending beyond a rear face of said wall,

an elongated headed screw having a length greater than the length of said passage formed for threadably engaging the walls of said bore and dimensioned to expand said member into frictional engagement with a wall of said passage for preventing rotation of said member and having a fully inserted position wherein said head is in engagement with a front face of said wall and an end of said member,

said material and form of said member cooperating to foreshorten and twist in said lead portion upon rotation of said screw in said fully inserted position for deforming said lead portion into locking engagement with said rear face of said wall.

4. A screw anchoring device for anchoring in a passage in a wall comprising:

an elongated tubular member of soft elastic material with a substantially smooth uninterrupted cylindrical exterior surface and having a hardness ranging between 43-52 Shore D formed with a bore and a plurality of internal radially projecting slots extending from said bore and having a lead portion,

said member being adapted for axial receipt of a headed screw threadably engaging the walls of said bore References Cited by the Examiner UNITED STATES PATENTS 2,125,018 7/ 1938 Hamill -70 2,918,841 12/ 1959 Poupitch 85-70 FOREIGN PATENTS 202,089 6/ 1956 Australia. 23 7,092 1/ 1962 Australia. I 1,342,704 9/ 1963 France. 1,354,587 1/ 1964 France.

598,730 2/ 1948 Great Britain.

CARL W. TOMLIN, Primary Examiner.

M. PARSONS, IR., Assistant Examiner. 

1. A SCREW ANCHORING DEVICE FOR ANCHORING IN A PASSAGE IN A WALL COMPRISING: AN ELONGATED TUBULAR MEMBER OF SOFT ELASTIC MATERIAL WITH A SUBSTANTIALLY SMOOTH UNINTERRUPTED CYLINDRICAL EXTERIOR SURFACE AND HAVING A HARDNESS RANGING BETWEEN 43-52 SHORE D FORMED WITH A BORE AND A PLURALITY OF INTERNAL RADIALLY PROJECTING SLOTS EXTENDING FROM SAID BORE AND HAVING A LEAD PORTION DIMENSIONED TO EXTEND BEYOND A REAR FACE OF SAID WALL, SAID MEMBER BEING ADAPTED FOR AXIAL RECEIPT OF A HEADED SCREW THREADABLY ENGAGING THE WALLS OF SAID BORE WHEREBY SAID MEMBER IS EXPANDED INTO FRICTIONAL ENGAGEMENT WITH A WALL OF SAID PASSAGE TO PREVENT ROTATION OF SAID MEMBER, AND SAID MATERIAL AND FORM OF SAID MEMBER FUNCTIONING TO FORESHORTEN AND TWIST IN SAID LEAD PORTION UPON ROTATION OF SAID SCREW WHEN SAID HEAD IS IN ENGAGEMENT WITH AN END DISTANT FROM SAID LEAD PORTION FOR DEFORING SAID LEAD PORTION INTO LOCKING ENGAGEMENT WITH SAID REAR FACES OF SAID WALL. 